1. Field
The present disclosure generally relates to the fields of biofuels and polysaccharide hydrolysis. More specifically, it relates to the use of amino acids as salts or with acids to hydrolyze polysaccharides and cellulosics.
2. Related Art
Cellulose is one of the most abundant materials on earth, found in every plant, tree and crop. Although it is used in some commercial processes, a vast majority of cellulose is tossed as waste in the form of corn husks, wood shavings, and other plant by-products. There are many documented attempts in the literature to utilize this waste and transform the polysaccharide in to simple sugars, which can then be fermented by yeast to produce so called bioethanol for biofuels or treated by algae to produce biodiesel for biofuels. However, there are still many problems that keep this from being commercialized. One of the biggest issues is the sturdiness of cellulose; it is very difficult to break down. There are two main methods of achieving this, inorganic acid hydrolysis and enzymatic hydrolysis, each of which has its own benefits and downfalls.
Enzymatic hydrolysis uses specialized enzymes to hydrolyze cellulose at fairly low temperatures. It can obtain high yields and enzymes cannot be easily separated from the mixture after usage. The concern with an industrial scale process using enzymes is that they have a relatively short life and must constantly be replaced—a very costly expenditure which has prevented its large scale use (Badger, 2002).
Acid hydrolysis focuses on the use of strong inorganic acids such as hydrochloric or sulfuric acid. These can be used in high concentration at relatively low temperatures (less than 80° C.) to receive high yields of sugar. However, these acids are very corrosive and require expensive alloy equipment, as well as being dangerous to workers and generate waste solution that must be treated before disposal. Additionally, for the process to be efficient, a cheaper method of recycling the acid is needed. Without recycling, the acid must be neutralized and properly disposed of before the sugar can be fully utilized. Low strong acid concentrations can be used in place of strong acids; however, this requires much higher temperatures to achieve decent yields and results in byproducts that are poisonous to yeast and bacteria (Badger 2002; Taherzadeh and Karimi, 2007). Similarly, the use of environmentally friendly acids that obtain similar hydrolysis rates to that of the caustic acids are of particular interest.